Particle acceleration in relativistic collisionless shocks: Fermi process at last?
read the original abstract
We present evidence that relativistic shocks propagating in unmagnetized plasmas can self-consistently accelerate particles. We use long-term two-dimensional particle-in-cell simulations to study the well-developed shock structure in unmagnetized pair plasma. The particle spectrum downstream of such a shock consists of two components: a relativistic Maxwellian, with characteristic temperature set by the upstream kinetic energy of the flow, and a high-energy tail, extending to energies >100 times that of the thermal peak. This tail is best fitted as a power law in energy with index -2.4+-0.1, modified by an exponential cutoff. The cutoff moves to higher energies with time of the simulation, leaving a larger power law range. The number of particles in the tail is ~1% of the downstream population, and they carry ~10% of the kinetic energy in the downstream. Upon investigation of the trajectories of particles in the tail, we find that the energy gains occur as particles bounce between the upstream and downstream regions in the magnetic fields generated by the Weibel instability. We compare this mechanism to the first order Fermi acceleration, and set a lower limit on the efficiency of shock acceleration process.
This paper has not been read by Pith yet.
Forward citations
Cited by 5 Pith papers
-
Deep Newtonian Afterglows: Theoretical Light Curves for Quasi-spherical Outflows
An analytical model for multiwavelength synchrotron emission from decelerated quasi-spherical ejecta with energy injection in stratified environments is developed for the deep Newtonian regime of GRB afterglows.
-
GRB 250706B/C: Insight-HXMT Discovery of a High-Luminosity Burst as a Candidate for Fallback-Regulated Accretion in the Prompt Emission
GRB 250706B/C exhibits temporal features consistent with fallback-regulated accretion operating on a high-luminosity branch in a collapsar.
-
Signatures of Two Distinct Epochs of FRB 20240114A from January to August 2024 Based on its Energy and Waiting Time Analysis
FRB 20240114A shows two epochs with distinct energy distribution indices and waiting time statistics, suggesting different burst types before and after March 21 2024.
-
A 0.03 Hz Radio Quasi-periodic Oscillation During the 2025 Flare of GRS 1915+105
A recurring 0.03 Hz radio QPO was detected in the 2025 flare of GRS 1915+105 at >5.9 sigma in one epoch, identical across S- and X-bands and prior years, indicating an intrinsic accretion-jet timescale.
-
Early Optical Follow-up of Gamma-Ray Bursts: The Critical Role of Robotic Telescopes
A review of early optical GRB features including prompt emission, reverse shocks, and afterglow onset, highlighting robotic telescopes' role in constraining jet Lorentz factors and magnetization.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.